Mobile terminal and chargeable communication module

ABSTRACT

A mobile terminal is provided with a housing, a circuit board included in the housing and having a thickness direction normal to a plane of the circuit board, a battery pack included in the housing, and a non-contact charging module included in the housing. The non-contact charging module includes a charging coil formed of a wound conducting wire; a communication coil arranged adjacent to the charging coil; and a magnetic sheet on which the charging coil and the communication coil are arranged. The magnetic sheet has four edges that collectively define a rectangular profile of the magnetic sheet, and at most three pairs of adjacent edges respectively meet to form at most three corners. At least a portion of the non-contact charging module overlaps with the circuit board as viewed in the thickness direction of the circuit board.

RELATED APPLICATIONS

This is a CONTINUATION of U.S. Pat. Application No. 16/746,573, filedJan. 17, 2020, which is a CONTINUATION of U.S. Pat. Application No.16/359,590, filed Mar. 20, 2019, now U.S. Pat. No. 10,574,090, which isa CONTINUATION of U.S. Pat. Application No. 15/480,174, filed Apr. 5,2017, now U.S. Pat. No. 10,291,069, which is a CONTINUATION of U.S. Pat.Application No. 14/410,556, filed Dec. 22, 2014, now U.S. Pat. No.9,667,086, which is a U.S. National Stage Application under 35 U.S.C.371 of International Application No. PCT/JP2013/003317, filed May 24,2013, which claims priority to Japanese Patent Application No.2012-145962, filed Jun. 28, 2012, the contents of which are incorporatedherein by reference.

BACKGROUND Technical Field

The present invention relates to a mobile terminal which includes anon-contact charging module including a non-contact charging module andan NFC antenna.

Description of the Related Art

In recent years, NFC (Near Field Communication) antennas that utilizeRFID (Radio Frequency IDentification) technology and use radio waves inthe 13.56 MHz band and the like are being used as antennas that aremounted in communication apparatuses such as mobile terminal devices. Toimprove the communication efficiency, an NFC antenna is provided with amagnetic sheet that improves the communication efficiency in the 13.56MHz band and thus configured as an NFC antenna module. Technology hasalso been proposed in which a non-contact charging module is mounted ina communication apparatus, and the communication apparatus is charged bynon-contact charging. According to this technology, a power transmissioncoil is disposed on the charger side and a power reception coil isprovided on the communication apparatus side, electromagnetic inductionis generated between the two coils at a frequency in a band betweenapproximately 100 kHz and 200 kHz to thereby transfer electric powerfrom the charger to the communication apparatus side. To improve thecommunication efficiency, the non-contact charging module is alsoprovided with a magnetic sheet that improves the efficiency ofcommunication in the band between approximately 100 kHz and 200 kHz.

Mobile terminals that include such NFC modules and non-contact chargingmodules have also been proposed (for example, see PTL 1).

CITATION LIST Patent Literature PTL 1

Japanese Patent No. 4669560

BRIEF SUMMARY Technical Problem

The term “NFC” refers to short-range wireless communication thatachieves communication by electromagnetic induction using a frequency inthe 13.56 MHz band. Further, non-contact charging transmits power byelectromagnetic induction using a frequency in a band betweenapproximately 100 kHz and 200 kHz. Accordingly, an optimal magneticsheet for achieving highly efficient communication (power transmission)in the respective frequency bands differs between an NFC module and anon-contact charging module. On the other hand, since both the NFCmodule and the non-contact charging module perform communication (powertransmission) by electromagnetic induction, the NFC module and thenon-contact charging module are liable to interfere with each other.That is, there is a possibility that when one of the modules isperforming communication, the other module will take some of themagnetic flux, and there is also the possibility that an eddy currentwill be generated in the other coil and weaken electromagnetic inductionof the one module that is performing communication.

Therefore, in PTL 1, the NFC module and the non-contact charging moduleeach include a magnetic sheet and are each arranged as a module, whichin turn hinders miniaturization of the communication apparatus. Thecommunication directions of the NFC module and the non-contact chargingmodule are made to differ so that mutual interference does not arisewhen the respective modules perform communication, and as a result thecommunication apparatus is extremely inconvenient because thecommunication surface changes depending on the kind of communication. Inaddition, in recent years there has been an increase in the use ofsmartphones in which a large proportion of one surface of the casingserves as a display portion, so that if the aforementioned communicationapparatus is applied to a smartphone it is necessary to perform one ofthe kinds of communication on the surface where the display sectionexists.

Also, when the non-contact charging module is provided in the mobileterminal, downsizing the mobile terminal is difficult and there is aroom for improvement.

An object of the present invention is to provide a mobile terminal thatmay achieve a reduction of thickness by making a non-contact chargingcoil, an NFC antenna, and a magnetic sheet into a single module, andthat may achieve a communication and a power transmission in the samedirection. Also, another object of the present invention is to improveboth power transmission efficiency of the non-contact charging andcommunication efficiency of NFC communication by laminating two types ofmagnetic sheets.

Solution to Problem

The mobile terminal of the present invention comprises a housing, abattery pack contained in the housing, and a non-contact charging modulecontained in the housing. The non-contact charging module includes acharging coil formed of a wound conducting wire, an NFC coil arranged soas to surround the charging coil, a first magnetic sheet supporting thecharging coil, and a second magnetic sheet placed on the first magneticsheet and supporting the NFC coil. The battery pack is arranged in afirst area in a plane normal to a thickness direction of the housing,and the non-contact charging module is arranged in a second areaadjacent to the first area. The non-contact charging module overlapswith a cross point between a first center line of the second area, whichextends in parallel to an interface between the first area and thesecond area, and a second center line of the second area, which extendsorthogonal to the interface and extends in a width direction of thehousing.

The battery pack is arranged in the first area and the non-contactcharging module is arranged in the second area.

Therefore, the battery pack and the non-contact charging module arearranged adjacent to each other. Thus, connecting the battery pack tothe non-contact charging module may be easy.

The non-contact charging module overlaps with a cross point between thefirst center line of the second area, which extends in parallel to aninterface between the first area and the second area, and a secondcenter line of the second area, which extends in a width direction ofthe housing.

Therefore, weight imbalance caused by non-contact charging module in theinterface direction of housing may be avoided.

The mobile terminal of the present invention comprises a housing, abattery pack contained in the housing, and a non-contact charging modulecontained in the housing. The non-contact charging module includes acharging coil formed of a wound conducting wire, an NFC coil arranged soas to surround the charging coil, a first magnetic sheet supporting thecharging coil, and a second magnetic sheet placed on the first magneticsheet and supporting the NFC coil. The battery pack is arranged in afirst area in a plane normal to a thickness direction of the housing,and the non-contact charging module is arranged in a second areaadjacent to the first area. The non-contact charging module overlapswith a cross point between a first center line of the second area, whichextends in parallel to an interface between the first area and thesecond area, and a second center line of the second area, which extendsorthogonal to the interface and extends in a width direction of thebattery pack.

The battery pack is arranged in the first area and the non-contactcharging module is arranged in the second area.

Therefore, the battery pack and the non-contact charging module arearranged adjacent to each other. Thus, connecting the battery pack tothe secondary-side non-contact charging module may be easy.

The non-contact charging module overlaps with a cross point between thefirst center line of the second area, which extends in parallel to aninterface between the first area and the second area, and a secondcenter line of the second area, which extends in a width direction ofthe battery pack.

Therefore, weight imbalance caused by non-contact charging module in theinterface direction of battery pack may be avoided.

The mobile terminal of the present invention comprises a housing, abattery pack contained in the housing, and a non-contact charging modulecontained in the housing. The non-contact charging module includes acharging coil formed of a wound conducting wire, an NFC coil arranged soas to surround the charging coil, a first magnetic sheet supporting thecharging coil, and a second magnetic sheet placed on the first magneticsheet and supporting the NFC coil. The battery pack is arranged in afirst area in a plane normal to a thickness direction of the housing,and the non-contact charging module is arranged in a second areaadjacent to the first area. The non-contact charging module is arrangedon a side closer to the first area relative to a first center line ofthe second area extending in parallel to an interface between the firstarea and the second area.

The battery pack is arranged in the first area and the non-contactcharging module is arranged in the second area.

Therefore, the battery pack and the non-contact charging module arearranged adjacent to each other. Thus, connecting the battery pack tothe non-contact charging module may be easy.

The non-contact charging module is arranged on a side closer to thefirst area relative to the first center line of the second areaextending in parallel to the interface between the first area and thesecond area.

Therefore, the weight of non-contact charging module is not biased to anopposite side of the first area relative to the first center line of thesecond area. Thus, causing discomfort to a user may be avoided.

Advantageous Effects of Invention

According to the present invention, a non-contact charging module and acommunication apparatus that enable a reduction in size by making anon-contact charging coil, an NFC antenna, and a magnetic sheet into asingle module, that can ease adverse effects by modularization and thatalso enable communication and power transmission in the same direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a mobile terminal according toa first embodiment of the present invention.

FIG. 2A is a plane view of a mobile terminal and FIG. 2B is a side viewof a mobile terminal according to a first embodiment.

FIG. 3 is a cross-section view of a circuit board and a secondary-sidenon-contact charging module of a first embodiment.

FIGS. 4A to 4E are an exploded view of a secondary-side non-contactcharging module according to a first embodiment.

FIGS. 5A to 5D illustrate relations between a primary-side non-contactcharging module that includes a magnet, and a charging coil;

FIG. 6 illustrates a relation between the size of an inner diameter of ahollow portion of a charging coil and an L value of the charging coilwhen an outer diameter of the hollow portion of the charging coil iskept constant with respect to a case where a magnet is provided in aprimary-side non-contact charging module and a case where a magnet isnot provided therein.

FIG. 7 illustrates a relation between an L value of a charging coil anda percentage of hollowing of a center portion with respect to a casewhere a magnet is provided in a primary-side non-contact charging moduleand a case where a magnet is not provided therein.

FIGS. 8A to 8D illustrate a secondary-side non-contact charging moduleaccording to a first embodiment.

FIG. 9 is a schematic diagram illustrating a first magnetic sheet thatincludes an L-shaped slit according to a first embodiment.

FIGS. 10A to 10C illustrate a frequency characteristic of a firstmagnetic sheet and a second magnetic sheet according to a firstembodiment.

FIG. 11 is a plane view explaining a charger which charges asecondary-side non-contact charging module according to a firstembodiment.

FIG. 12 is a perspective view illustrating an example of charging asecondary-side non-contact charging module according to a firstembodiment.

FIG. 13 is a plane view of a mobile terminal according to a secondembodiment.

FIG. 14 is a plane view of a mobile terminal according to a thirdembodiment.

DETAILED DESCRIPTION

An embodiment of a mobile terminal according to an embodiment of thepresent invention will be described with reference to the accompanyingdrawings.

The First Embodiment

As shown in FIG. 1 , a mobile terminal 10 includes a housing 11, acommunicating hole 12 through which the inside and the outside of thehousing 11 communicate, a camera unit 16 mounted on a circuit board 14,a battery pack housed in the housing 11, and a secondary-sidenon-contact charging module (non-contact charging module) 20.

Furthermore, the mobile terminal 10 includes a heat dissipating sheet 22(which is shown in FIG. 2B) provided on the secondary-side non-contactcharging module 20, a display unit 24 provided at a side of an aperture11A of the housing 11, and a protection cover 26 covering the displayunit 24.

As described in FIGS. 2A and 2B, the housing 11 is formed into asubstantially rectangular shape in a plane normal to a thicknessdirection of the housing 11. The housing 11 includes a first areapositioned at the opposite of the communicating hole 12 in a planenormal and a second area 32 positioned adjacent to the first area 31.

The battery pack 18 is located in the first area 31 and thesecondary-side non-contact charging module 20 and the camera unit 16 arelocated in the second area 32.

As described in FIG. 3 , the circuit board 14 includes a base substrate34 located in the second area 32 of the housing 11 and a plurality ofelectronic components which are located on a side 34A facing thesecondary-side non-contact charging module 20.

Also, the circuit board 14 is provided with a shield case 36 coveringthe plurality of electronic components which are located on the side 34Afacing the secondary-side non-contact charging module 20.

The camera unit 16 is located on the side 34A facing the secondary-sidenon-contact charging module 20 of the base substrate 34 and includes acamera module capable of taking an image through the communicating hole12.

As describe in FIGS. 2A and 2B, the battery pack 18 is formed into asubstantially rectangular shape and located in the first area 31 in aplane normal to the thickness direction of the housing 11.

As described in FIG. 4A, the secondary-side non-contact charging module20 is located in the second area 32 of the housing 11 (as shown in FIG.2A). And the secondary-side non-contact charging module 20 includes acharging coil 41 that includes a wound conducting wire 42 and a NFC coil43 that is disposed so as to surround charging coil 41.

Also, the secondary-side non-contact charging module 20 includes a firstmagnetic sheet 44 that supports the charging coil 41 and a secondmagnetic sheet 45 that is placed the NFC coil 43 from the samedirection.

An insulative double-faced tape or adhesive or the like is used toadhere the upper face of first magnetic sheet 44 and the lower face ofsecond magnetic sheet 45, to adhere the upper face of first magneticsheet 44 and the lower face of the charging coil 41, and to adhere theupper face of second magnetic sheet 45 and the lower face of the NFCcoil 43. It is advantageous to arrange the entire charging coil 41 onfirst magnetic sheet 44 so as not to protrude therefrom, and to arrangethe entire NFC coil 43 on second magnetic sheet 45 so as not to protrudetherefrom. It is advantageous to arrange second magnetic sheet 45 so asnot to protrude from first magnetic sheet 44. Adopting such aconfiguration can improve the communication efficiency of both thecharging coil 41 and the NFC coil 43. Note that slit 48 is formed infirst magnetic sheet 44. The shape of slit 48 may be the shape shown inFIG. 4A (a shape as shown in FIG. 9 that is described later), or may bethe shape shown in FIG. 4D. Also, in FIG. 4A, although the slit 48 doesnot extend to a center portion 44B, the slit 48 may extend to a centerportion 44B. This may enable a whole of two leg portions 432 a and 432 bto be completely housed in the slit 48.

The following is an detailed explanation of the charging coil 41, theNFC coil 43, the first magnetic sheet 44, and the second magnetic sheet45.

Regarding Charging Coil

The charging coil 414 will be described in detail using FIG. 4B.

In the present embodiment, charging coil 41 is wound in a substantiallysquare shape, but may be wound in any shape such as a substantiallyrectangular shape including a substantially oblong shape, a circularshape, an elliptical shape, and a polygonal shape.

The charging coil 41 has two leg portions (terminals) 432 a and 432 b asa starting end and a terminating end thereof, and includes a litz wireconstituted by around 8 to 15 conducting wires having a diameter ofapproximately 0.1 mm or a plurality of wires (preferably, around 2 to 15conducting wires having a diameter of 0.08 mm to 0.3 mm) that is woundaround a hollow portion as though to draw a swirl on the surface. Forexample, in the case of a coil including a wound litz wire made of 12conducting wires having a diameter of 0.1 mm, in comparison to a coilincluding a single wound conducting wire having the same cross-sectionalarea, the alternating-current resistance decreases considerably due tothe skin effect. If the alternating-current resistance decreases whilethe coil is operating, heat generation by the coil decreases and thuscharging coil 41 that has favorable thermal properties can be realized.At this time, if a litz wire that includes 8 to 15 conducting wireshaving a diameter of 0.08 mm to 1.5 mm is used, favorable power transferefficiency can be achieved. If a single wire is used, it is advantageousto use a conducting wire having a diameter between 0.2 mm and 1 mm.Further, for example, a configuration may also be adopted in which,similarly to a litz wire, a single conducting wire is formed of threeconducting wires having a diameter of 0.2 mm and two conducting wireshaving a diameter of 0.3 mm. Terminals 432 a and 432 b as a currentsupply section supply a current from a commercial power source that isan external power source to charging coil 41. Note that an amount ofcurrent that flows through charging coil 41 is between approximately 0.4A and 2 A. In the present embodiment the amount of current is 0.7 A.

In charging coil 41 of the present embodiment, a distance between facingsides (a length of one side) of the hollow portion having asubstantially square shape is 20 mm (between 15 mm and 25 mm ispreferable), and a distance between facing sides (a length of one side)at an outer edge of the substantially square shape is 35 mm (between 25mm and 45 mm is preferable). Charging coil 41 is wound in a donut shape.In a case where charging coil 41 is wound in a substantially oblongshape, with respect to facing sides of the hollow portion of thesubstantially oblong shape, a distance between short sides (a length ofone side) is 15 mm (between 10 mm and 20 mm is preferable) and adistance between long sides (a length of one side) is 23 mm (between 15mm and 30 mm is preferable). Further, with respect to facing sides at anouter edge of a substantially square shape, a distance between shortsides (a length of one side) is 28 mm (between 15 mm and 35 mm ispreferable) and a distance between long sides (a length of one side) is36 mm (between 20 mm and 45 mm is preferable). In a case where chargingcoil 41 is wound in a circular shape, the diameter of the hollow portionis 20 mm (between 10 mm and 25 mm is preferable) and the diameter of anouter edge of the circular shape is 35 mm (between 25 mm and 45 mm ispreferable).

Further, in some cases charging coil 41 utilizes a magnet for alignmentwith a coil of a non-contact charging module inside a charger thatsupplies power to charging coil 41 as a counterpart for powertransmission. A magnet in such a case is defined by the standard (WPC)as a circular (coin shaped) neodymium magnet having a diameter ofapproximately 15.5 mm (approximately 10 mm to 20 mm) and a thickness ofapproximately 1.5 to 2 mm or the like. A favorable strength of themagnet is approximately 75 mT to 150 mT. Since an interval between acoil of the primary-side non-contact charging module and charging coil41 is around 2 to 5 mm, it is possible to adequately perform alignmentusing such a magnet. The magnet is disposed in a hollow portion of thenon-contact charging module coil on the primary side or secondary side.In the present embodiment, the magnet is disposed in the hollow portionof charging coil 41.

That is, for example, the following methods may be mentioned as analigning method. For example, a method is available in which aprotruding portion is formed in a charging surface of a charger, arecessed portion is formed in an electronic device on the secondaryside, and the protruding portion is fitted into the recessed portion tothereby physically (geometrically) perform compulsory aligning. A methodis also available in which a magnet is mounted on at least one of theprimary side and secondary side, and alignment is performed byattraction between the respective magnets or between a magnet on oneside and a magnetic sheet on the other side. As described in FIG. 11A, amethod is also available in which a large number of coils 53 areprovided in a wide area in the primary-side non-contact charging module52 of the charger 50(the primary-side) so that the mobile terminal 10(the secondary-side) can be charged anywhere on the surface of thecharger 50. As described in FIG. 11B, a method is also available inwhich the coil 53 of the primary-side non-contact charging module 52 ofthe charger 50 (the primary-side) is moved in a direction of the X axialand the Y axial so that the coil 53 can move to a position of thecharging coil 41 of the mobile terminal 10 (the secondary-side).Furthermore, as described in FIG. 11C, a method is also available inwhich the coil 53 of the primary-side non-contact charging module 52 ofthe charger 50 (the primary-side) is formed to be relatively large sothat the charging coil 41 of the mobile terminal 10 (the secondary-side)can be aligned with the coil 53.

Thus, various methods can be mentioned as common methods for aligningthe coils of the primary-side (charging-side) non-contact chargingmodule and the secondary-side (charged-side) non-contact chargingmodule, and the methods are divided into methods that use a magnet andmethods that do not use a magnet. The secondary-side non-contactcharging module 20 is configured to be adaptable to both of a primaryside (charging-side) non-contact charging module that uses a magnet anda primary-side non-contact charging module that does not use a magnet.Therefore, charging can be performed regardless of the type ofprimary-side non-contact charging module, which in turn, improves theconvenience of the module.

The influence that a magnet has on the power transmission efficiency ofnon-contact charging module 100 will be described.

When magnetic flux for electromagnetic induction is generated betweenthe primary-side non-contact charging module and non-contact chargingmodule 20 to transmit power, the presence of a magnet between or aroundthe primary-side non-contact charging module and non-contact chargingmodule 20 leads extension of the magnetic flux to avoid the magnet.Otherwise, the magnetic flux that passes through the magnet becomes aneddy current or generates heat in the magnet and is lost. Furthermore,if the magnet is disposed in the vicinity of first magnetic sheet 44,first magnetic sheet 44 that is in the vicinity of the magnet saturatesand the magnetic permeability thereof decreases. Therefore, the magnetthat is included in the primary-side non-contact charging module maydecrease an L value of charging coil 41. As a result, transmissionefficiency between the non-contact charging modules will decrease. Toprevent this, in the present embodiment the hollow portion of chargingcoil 41 is made larger than the magnet. That is, the area of the hollowportion is made larger than the area of a circular face of thecoin-shaped magnet, and an inside edge (portion surrounding the hollowportion) of charging coil 41 is configured to be located at a positionthat is on the outer side relative to the outer edge of the magnet.Further, because the diameter of the magnet is 15.5 mm or less, it issufficient to make the hollow portion larger than a circle having adiameter of 15.5 mm. As another method, charging coil 41 may be wound ina substantially oblong shape, and a diagonal of the hollow portionhaving a substantially oblong shape may be made longer than the diameter(maximum 15.5 mm) of the magnet. As a result, since the corner portions(four corners) at which the magnetic flux concentrates of charging coil41 that is wound in a substantially oblong shape are positioned on theouter side relative to the magnet, the influence of the magnet can besuppressed. Effects obtained by employing the above describedconfiguration are described hereunder.

FIGS. 5A to 5D illustrate relations between the primary-side non-contactcharging module including the magnet, and the charging coil. FIG. 5Aillustrates a case where the aligning magnet is used when the innerwidth of the wound charging coil is small. FIG. 5B illustrates a casewhere the aligning magnet is used when the inner width of the woundcharging coil is large. FIG. 5C illustrates a case where the aligningmagnet is not used when the inner width of the wound charging coil issmall. FIG. 5D illustrates a case where the aligning magnet is not usedwhen the inner width of the wound charging coil is large.

Primary-side non-contact charging module 200 that is disposed inside thecharger includes primary-side coil 210, magnet 220, and a magnetic sheet(not illustrated in the drawings). In FIGS. 5A to 5D, first magneticsheet 44, second magnetic sheet 45, and charging coil 41 insidenon-contact charging module 20 are schematically illustrated.

Secondary-side non-contact charging module 20 and primary-sidenon-contact charging module 200 are aligned so that primary-side coil210and charging coil 41 face each other. A magnetic field is generatedbetween inner portion 211 of primary-side coil 210 and inner portion 133of charging coil 41 and power is transmitted. Inner portion 211 andinner portion 133 face each other. Inner portion 211 and inner portion33 are close to magnet 220 and are liable to be adversely affected bymagnet 220.

In addition, because magnet 220 is disposed in the vicinity of firstmagnetic sheet 44 and second magnetic sheet 45, the magneticpermeability of the magnetic sheets in the vicinity of magnet 220decreases. Naturally, second magnetic sheet 45 is closer than secondmagnetic sheet 45 to magnet 220, and is more liable to be affected bymagnet 220. Therefore, magnet 220 included in primary-side non-contactcharging module 200 weakens the magnetic flux of primary-side coil 210and charging coil 41, particularly, at inner portion 211 and innerportion 133, and exerts an adverse effect. As a result, the transmissionefficiency of the non-contact charging decreases. Accordingly, in thecase illustrated in FIG. 5A, inner portion 133 that is liable to beadversely affected by magnet 220 is large.

In contrast, in the case illustrated in FIG. 5C in which a magnet is notused, the L value increases because the number of turns of charging coil41 is large. As a result, since there is a significant decrease in thenumerical value from the L value in FIG. 5C to the L value in FIG. 5A,when using a wound coil having a small inner width, the L-value decreaserate with respect to an L value in a case where magnet 220 is includedfor alignment and an L value in a case where magnet 220 is not includedis extremely large.

Further, if the inner width of charging coil 41 is smaller than thediameter of magnet 220 as illustrated in FIG. 5A, charging coil 41 isdirectly adversely affected by magnet 220 to a degree that correspondsto the area of charging coil 41 that faces magnet 220. Accordingly, itis better for the inner width of charging coil 41 to be larger than thediameter of magnet 220.

In contrast, when the inner width of charging coil 41 is large asillustrated in FIG. 5B, inner portion 133 that is liable to be adverselyaffected by magnet 220 is extremely small. In the case illustrated inFIG. 5D, the L value is smaller than in FIG. 5C because the number ofturns of charging coil 41 is less. Consequently, because a decrease inthe numerical value from the L value in the case illustrated in FIG. 5Dto the L value in the case illustrated in FIG. 5B is small, the L-valuedecrease rate can be suppressed to a small amount in the case of coilsthat have a large inner width. Further, as the inner width of chargingcoil 41 increases, the influence of magnet 220 can be suppressed becausethe distance from magnet 220 to the edge of the hollow portion ofcharging coil 41 increases.

Since communication module 20 is mounted in an electronic device or thelike, charging coil 41 cannot be made larger than a certain size.Accordingly, if the inner width of charging coil 41 is made large toreduce the adverse effects from magnet 220, the number of turns willdecrease and the L value itself will decrease regardless of the presenceor absence of a magnet. Therefore, charging coil 41 can be increased tothe maximum size in a case where the area of magnet 220 and the area ofthe hollow portion of charging coil 41 are substantially the same (theouter diameter of magnet 220 is about 0 to 2 mm smaller than the innerwidth of charging coil 41, or the area of magnet 220 is a proportion ofabout 75% to 95% relative to the area of the hollow portion of chargingcoil 41). Hence, the accuracy of the alignment between the primary-sidenon-contact charging module and the secondary-side non-contact chargingmodule can be improved. Further, if the area of magnet 220 is less thanthe area of the hollow portion of charging coil 41 (the outer diameterof magnet 220 is about 2 to 8 mm smaller than the inner width ofcharging coil 41, or the area of magnet 220 is a proportion of about 45%to 75% relative to the area of the hollow portion of charging coil 41),even if there are variations in the alignment accuracy, it is possibleto ensure that magnet 220 is not present at a portion at which innerportion 211 and inner portion 33 face each other.

In addition, as charging coil 41 that is mounted in non-contact chargingmodule 20 having the same lateral width and vertical width, theinfluence of magnet 220 can be suppressed more by winding the coil in asubstantially rectangular shape rather than in a circular shape. Thatis, comparing a circular coil in which the diameter of a hollow portionis represented by “x” and a substantially square coil in which adistance between facing sides of the hollow portion (a length of oneside) is represented by “x,” if conducting wires having the samediameter as each other are wound with the same number of turns, therespective conducting wires will be housed in respective non-contactcharging modules 100 that have the same width. In such case, length y ofa diagonal of the hollow portion of the substantially square-shaped coilwill be such that y>x. Accordingly, if the diameter of magnet 220 istaken as “m,” a distance (x-m) between the innermost edge of thecircular coil and magnet 220 is always constant (x>m). On the otherhand, a distance between the innermost edge of a substantiallyrectangular coil and magnet 220 is a minimum of (x-m), and is a maximumof (y-m) at corner portions 431 a to 431 d. When charging coil 41includes corners such as corner portions 431 a to 431d, magnetic fluxconcentrates at the corners during power transmission. That is, cornerportions 431 a to 431 d at which the most magnetic flux concentrates arefurthest from magnet 220, and moreover, the width (size) of non-contactcharging module 100 does not change. Accordingly, the power transmissionefficiency of power reception coil 30 can be improved without makingnon-contact charging module 100 a large size.

The size of charging coil 41 can be reduced further if charging coil 41is wound in a substantially oblong shape. That is, even if a short sideof a hollow portion that is a substantially oblong shape is smaller thanm, as long as a long side thereof is larger than m it is possible todispose four corner portions outside of the outer circumference ofmagnet 220. Accordingly, when charging coil 41 is wound in asubstantially oblong shape around a hollow portion having asubstantially oblong shape, charging coil 41 can be wound in a favorablemanner as long as at least the long side of the hollow portion is largerthan m. Note that, the foregoing description of a configuration in whichthe innermost edge of charging coil 41is on the outer side of magnet 220that is provided in primary-side non-contact charging module 200 and inwhich four corners of the substantially rectangular hollow portion ofcharging coil 41 that is wound in a substantially rectangular shape areon the outside of magnet 220 refers to a configuration as shown in FIG.5B. That is, the foregoing describes a fact that when an edge of thecircular face of magnet 220 is extended in the stacking direction andcaused to extend as far as non-contact charging module 20, a regionsurrounded by the extension line is contained within the hollow portionof charging coil 41.

FIG. 6 illustrates a relation between the size of the inner diameter ofthe wound charging coil and the L value of the charging coil when theouter diameter of the wound charging coil is kept constant, with respectto a case where a magnet is provided in the primary-side non-contactcharging module and a case where the magnet is not provided therein. Asshown in FIG. 6 , when the size of magnet 220 and the outer diameter ofcharging coil 41 are kept constant, the influence of magnet 220 oncharging coil 41 decreases as the number of turns of charging coil 41decreases and the inner diameter of charging coil 41 increases. That is,the L value of charging coil 41 in a case where magnet 220 is utilizedfor alignment between the primary-side non-contact charging module andthe secondary-side non-contact charging module and the L value ofcharging coil 41 in a case where magnet 220 is not utilized foralignment approach each other. Accordingly, a resonance frequency whenmagnet 220 is used and a resonance frequency when magnet 220 is not usedbecome extremely similar values. At such time, the outer diameter of thewound coil is uniformly set to 30 mm. Further, by making the distancebetween the edge of the hollow portion of the charging coil 41(innermost edge of charging coil 41) and the outer edge of magnet 220greater than 0 mm and less than 6 mm, the L values in the case ofutilizing magnet 220 and the case of not utilizing magnet 220 can bemade similar to each other while maintaining the L values at 15 µH ormore.

The conducting wire of charging coil 41 may be a single conducting wirethat is stacked in a plurality of stages, and the stacking direction inthis case is the same as the stacking direction in which first magneticsheet 44 and charging coil 41 are stacked. At such time, by stacking thelayers of conducting wire that are arranged in the vertical directionwith a space interposed in between, stray capacitance between conductingwire on an upper stage and conducting wire on a lower stage decreases,and the alternating-current resistance of charging coil 41 can besuppressed to a small amount. Further, the thickness of charging coil 41can be minimized by winding the conducting wire densely. By stacking theconducting wire in this manner, the number of turns of charging coil 41can be increased to thereby improve the L value. However, in comparisonto winding of the charging coil 41 in a plurality of stages in thestacking direction, winding of charging coil 41 in one stage can lowerthe alternating-current resistance of charging coil 41 and raise thetransmission efficiency.

If charging coil 41 is wound in a polygonal shape, corner portions(corners) 431 a to 431 d are provided as described below. Charging coil41 that is wound in a substantially square shape refers to a coil inwhich R (radius of a curve at the four corners) of corner portions 431 ato 431 d that are four corners of the hollow portion is equal to or lessthan 30% of the edge width of the hollow portion. That is, in FIG. 4B,in the substantially square hollow portion, the four corners have acurved shape. In comparison to right angled corners, the strength of theconducting wire at the four corners can be improved when the corners arecurved to some extent. However, if R is too large, there is almost nodifference from a circular coil and it will not be possible to obtaineffects that are only obtained with a substantially square charging coil41. It has been found that when the edge width of the hollow portion is,for example, 20 mm, and radius R of a curve at each of the four cornersis 6 mm or less, the influence of a magnet can be effectivelysuppressed. Further, when taking into account the strength of the fourcorners as described above, the greatest effect of the rectangular coildescribed above can be obtained by making radius R of a curve at each ofthe four corners an amount that corresponds to a proportion of 5 to 30%relative to the edge width of the substantially square hollow portion.Note that, even in the case of charging coil 41 wound in a substantiallyoblong shape, the effect of the substantially oblong coil describedabove can be obtained by making radius R of a curve at each of the fourcorners an amount that corresponds to a proportion of 5 to 30% relativeto the edge width (either one of a short side and a long side) of thesubstantially oblong hollow portion. Note that, in the presentembodiment, with respect to the four corners at the innermost end(hollow portion) of charging coil 41, R is 2 mm, and a preferable valuefor R is between 0.5 mm and 4 mm.

Further, when winding charging coil 41 in a rectangular shape,preferably, leg portions 432 a and 432 b are provided in the vicinity ofcorner portions 431 a to 431 d. When charging coil 41 is wound in acircular shape, irrespective of where leg portions 432 a and 432 b areprovided, leg portions 432 a and 432 b can be provided at a portion atwhich a planar coil portion is wound in a curve. When the conductingwire is wound in a curved shape, a force acts that tries to maintain thecurved shape thereof, and it is difficult for the overall shape to bebroken even if leg portions 32 a and 32 b are formed. In contrast, inthe case of a coil in which the conducting wire is wound in arectangular shape, there is a difference in the force with which thecoil tries to maintain the shape of the coil itself with respect to sideportions (linear portions) and corner portions. That is, at cornerportions 431 a to 431 d in FIG. 4B, a large force acts to try tomaintain the shape of charging coil 41. However, at each side portion, aforce that acts to try to maintain the shape of charging coil 41 issmall, and the conducting wire is liable to become uncoiled fromcharging coil 41in a manner in which the conducting wire pivots aroundthe curves at corner portions 431 a to 431 d. As a result, the number ofturns of charging coil 41 fluctuates by, for example, about ⅛ turn, andthe L value of charging coil 41 fluctuates. That is, the L value ofcharging coil 41 varies. Accordingly, it is favorable for winding startpoint 432 aa and winding end point 432 bb of the conducting wire whichis wound a plurality of times until winding end point 432 bb is formedto be adjacent to corner portions 431 a to 431 d. At this time, theconducting wire is bent to a larger degree in a gradual manner atwinding end point 432 bb compared to winding start point 432 aa. This isdone to enhance a force that tries to maintain the shape of leg portion432 b.

If the conducting wire is a litz wire, a force that tries to maintainthe shape of charging coil 41 is further enhanced. In the case of a litzwire, since the surface area per wire is large, if an adhesive or thelike is used to fix the shape of charging coil 41, it is easy to fix theshape thereof. In contrast, if the conducting wire is a single wire,because the surface area per conducting wire decreases, the surface areato be adhered decreases and the shape of charging coil 41 is liable tobecome uncoiled.

According to the present embodiment charging coil 41 is formed using aconducting wire having a circular sectional shape, but a conducting wirehaving a square sectional shape may be used as well. In the case ofusing a conducting wire having a circular sectional shape, since gapsarise between adjacent conducting wires, stray capacitance between theconducting wires decreases and the alternating-current resistance ofcharging coil 41 can be suppressed to a small amount.

Regarding NFC Coil

NFC coil 43 according to the present embodiment that is illustrated inFIG. 4C is an antenna that carries out short-range wirelesscommunication which performs communication by electromagnetic inductionusing the 13.56 MHz frequency, and a sheet antenna is generally usedtherefor.

NFC coil 43 includes second magnetic sheet 45 having a ferrite magneticbody as a principal component, protective members between which themagnetic sheet is interposed, a matching circuit, a terminal connectionsection, a substrate, a chip capacitor for matching and the like. NFCcoil 43 may be housed in a radio communication medium such as an IC cardor IC tag, or may be housed in a radio communication medium processingapparatus such as a reader or a reader/writer.

NFC coil 43 in an antenna pattern that is formed with a spiral-shapedconductive material (that is, is formed by winding a conducting wire).The spiral structure may be a spiral shape that has an open portion atthe center, and the shape thereof may any one of a circular shape, asubstantially rectangular shape, a substantially square shape, and apolygonal shape. In the present embodiment, NFC coil 43 is a rectangularshape, and particularly is a square shape. Adopting a spiral structurecauses a sufficient magnetic field to be generated and enablescommunication by generation of inductive power and mutual inductance.

Further, since a circuit can be formed directly on the surface of orinside second magnetic sheet 45, it is possible to form NFC coil 43,matching circuit, and terminal connection section directly on secondmagnetic sheet 45.

The matching circuit is constituted by a chip capacitor that is mountedso as to form a bridge with an electric conductor of NFC coil 43 that isformed on a substrate, and therefore the matching circuit can be formedon the NFC coil.

Connecting the matching circuit with the coil forms NFC coil 43 in whichthe resonance frequency of the antenna is adjusted to a desiredfrequency, which suppresses the occurrence of standing waves due tomismatching, and which operates stably with little loss. The chipcapacitor used as a matching element is mounted so as to form a bridgewith the electric conductor of NFC coil 43.

The substrate can be formed of a polyimide, PET, a glass-epoxysubstrate, an FPC substrate or the like. By using a polyimide or PET orthe like, NFC coil 43 that is thin and flexible can be formed byprinting or the like. According to the present embodiment, the substrateis constituted by an FPC substrate having a thickness of 0.2 mm.

Note that the above described NFC coil 43 is merely an example, and thepresent invention is not limited to the above described configuration ormaterials and the like.

NFC coil 43 can be formed in a thin condition by forming a conductingwire on a substrate by pattern printing. Unlike charging coil 41, theamount of current during communication is extremely small, so that NFCcoil 43 can be formed by pattern printing. The current is approximately0.2 A to 0.4 A. The width of NFC coil 43 is between 0.1 mm and 1 mm, andthe thickness is between 15 µm and 35 µm. In the present embodiment theconducting wire of NFC coil 43 is wound for four turns, and the numberof turns may be from two to six. The length of the sides of the outershape of NFC coil 43 is approximately 39 mm×39 mm (a preferable lengthof one side is between 30 mm and 60 mm), and the size of the substrateis approximately 39.6 mm×39.6 mm (a preferable length of one side isbetween 30 mm and 60 m). In a case where NFC coil 43 is wound in anoblong shape, with respect to the outer diameter of the substrate andNFC coil 43, preferably the length of a long side is between 40 mm and60 mm and the length of a short side is between 30 mm and 50 mm.Further, with respect to the four corners, R is between 0.1 mm and 0.3mm at the innermost edge of NFC coil 43 and R is between 0.2 mm and 0.4mm at the outermost edge thereof, and the four corners of the outermostedge necessarily curve more gradually than the four corners at theinnermost edge.

Regarding First Magnetic Sheet

First magnetic sheet 44 includes flat portion 44A on which charging coil41 and second magnetic sheet 45 are mounted, center portion 44B that issubstantially the center portion of flat portion 44A and thatcorresponds (faces) to the inside of the hollow region of charging coil41, and slit 48into which at least a part of the two leg portions 432 aand 432 b of charging coil 41 is inserted. Slit 48 is not limited to aslit shape that penetrates through first magnetic sheet 44 as shown inFIG. 4D, and may be formed in the shape of a recessed portion that doesnot penetrate therethrough. Forming slit 48 in a slit shape facilitatesmanufacture and makes it possible to securely house the conducting wire.On the other hand, forming slit 48 in the shape of a recessed portionmakes it possible to increase the volume of first magnetic sheet 44, andit is thereby possible to improve the L value of charging coil 41 andthe transmission efficiency. Center portion 44B may be formed in a shapethat, with respect to flat portion 12, is any one of a protrudingportion shape, a flat shape, a recessed portion shape, and the shape ofa through-hole. If center portion 44B is formed as a protruding portion,the magnetic flux of charging coil 41 can be strengthened. If centerportion 44B is flat, manufacturing is facilitated and charging coil 41can be easily mounted thereon, and furthermore, a balance can beachieved between the influence of an aligning magnet and the L value ofcharging coil 41 that is described later. A detailed description withrespect to a recessed portion shape and a through-hole is describedlater.

A Ni—Zn ferrite sheet, a Mn—Zn ferrite sheet, or a Mg—Zn ferrite sheetor the like can be used as first magnetic sheet 44. First magnetic sheet44 may be configured as a single layer, may be configured by stacking aplurality of sheets made of the same material in the thicknessdirection, or may be configured by stacking a plurality of differentmagnetic sheets in the thickness direction. It is preferable that, atleast, the magnetic permeability of first magnetic sheet 44 is 250 ormore and the saturation magnetic flux density thereof is 350 mT or more.

An amorphous metal can also be used as first magnetic sheet 44. The useof ferrite sheet (sintered body) as first magnetic sheet 44 isadvantageous in that the alternating-current resistance of charging coil41 can be reduced, while the use of amorphous metal as the magneticsheet is advantageous in that the thickness of charging coil 41 can bereduced.

First magnetic sheet 44 is substantially square within a size ofapproximately 40×40 mm (from 35 mm to 50 mm), and is formed in a sizethat is equal to or somewhat larger than the size of the substrate ofNFC coil 43. In a case where first magnetic sheet 44 is a substantiallyoblong shape, a short side thereof is 35 mm (from 25 mm to 45 mm) and along side is 45 mm (from 35 mm to 55 mm). The thickness thereof is 0.43mm (in practice, between 0.4 mm and 0.55 mm, and preferably between 0.3mm and 0.7 mm). It is desirable to form first magnetic sheet 44 in asize that is equal to or larger than the size of the outercircumferential edge of second magnetic sheet 45. First magnetic sheet44 may be a circular shape, a rectangular shape, a polygonal shape, or arectangular and polygonal shape having large curves at four corners.

Also, the secondary-side non-contact charging module 20 includes acharging coil 41 that includes a wound conducting wire 42 and a NFC coil43 that is disposed so as to surround charging coil 41. Also, thesecondary-side non-contact charging module 20 includes a first magneticsheet 44 that supports the charging coil 41 and a second magnetic sheet45 that is placed the NFC coil 43 from the same direction and a slit48provided on the first magnetic sheet 44. The leg portions 432 a and432 b are housed in the slit 48.

Slit 48 illustrated in FIG. 4D houses the conducting wire of at least apart of each of the two leg portions 432 a and 432 b that extend fromwinding start point 432 aa (innermost portion of coil) and winding endpoint 432 bb (outermost edge of coil) of charging coil 41 to lower edge414 of first magnetic sheet 44. Thus, slit 48 prevents the conductingwire from winding start point 32aa of the coil to leg portion 32 aoverlapping in the stacking direction at a planar winding portion ofcharging coil 41. In addition, slit 48 prevents leg portions 432 a and432 b overlapping in the stacking direction of NFC coil 43 and therebyincreasing the thickness of secondary-side non-contact charging module20.

Slit 48 is formed so that one end thereof is substantially perpendicularto an end (edge) of first magnetic sheet 44 that intersects therewith,and so as to contact center portion 44B of first magnetic sheet 44. In acase where charging coil 41 is circular, by forming slit 48 so as tooverlap with a tangent of center portion 44B (circular), leg portions432 a and 432 b can be formed without bending a winding start portion ofthe conducting wire. In a case where charging coil 41 is a substantiallyrectangular shape, by forming slit 48 so as to overlap with an extensionline of a side of center portion 44B (having a substantially rectangularshape), leg portions 432 a and 432 b can be formed without bending thewinding start portion of the conducting wire. The length of slit 48depends on the inner diameter of charging coil 41 and the size of firstmagnetic sheet 44. In the present embodiment, the length of slit 48 isbetween approximately 15 mm and 30 mm.

Slit 48 may also be formed at a portion at which an end (edge) of firstmagnetic sheet 44 and center portion 44B are closest to each other. Thatis, when charging coil 41 is circular, slit 48 is formed to beperpendicular to the end (edge) of first magnetic sheet 44 and a tangentof center portion 44B (circular), and is formed as a short slit.Further, when charging coil 41 is substantially rectangular, slit 48 isformed to be perpendicular to an end (edge) of first magnetic sheet 44and a side of center portion 44B (substantially rectangular), and isformed as a short slit. It is thereby possible to minimize the area inwhich slit 48 is formed and to improve the transmission efficiency of anon-contact power transmission device. Note that, in this case, thelength of slit 48 is approximately 5 mm to 20 mm. In both of theseconfigurations, the inner side end of the linear recessed portion orslit 48 is connected to center portion 44B.

Next, adverse effects on first magnetic sheet 44 produced by the magnetfor alignment described in the foregoing are described. As describedabove, when magnet 220 is provided in primary-side non-contact chargingmodule 200 for alignment, due to the influence of magnet 220, themagnetic permeability of first magnetic sheet 44 decreases at a portionthat is close to magnet 220 in particular. Accordingly, the L value ofcharging coil 41 varies significantly between a case where magnet 220for alignment is provided in primary-side non-contact charging module200 and a case where magnet 220 is not provided. It is thereforenecessary to provide the magnetic sheet such that the L value ofcharging coil 41 changes as little as possible between a case wheremagnet 220 is close thereto and a case where magnet 220 is not closethereto.

When the electronic device in which non-contact charging module ismounted is a mobile phone, in many cases non-contact charging module isdisposed between the case constituting the exterior package of themobile phone and a battery pack located inside the mobile phone, orbetween the case and a substrate located inside the case. In general,since the battery pack is a casing made of aluminum, the battery packadversely affects power transmission. This is because an eddy current isgenerated in the aluminum in a direction that weakens the magnetic fluxgenerated by the coil, and therefore the magnetic flux of the coil isweakened. For this reason, it is necessary to alleviate the influencewith respect to the aluminum by providing first magnetic sheet 44between the aluminum which is the exterior package of the battery packand charging coil 41 disposed on the exterior package thereof. Further,there is a possibility that an electronic component mounted on thesubstrate will interfere with power transmission of charging coil 41,and the electronic component and charging coil 41 will exert adverseeffects on each other. Consequently, it is necessary to provide amagnetic sheet or a metal film between the substrate and charging coil41, and suppress the mutual influences of the substrate and chargingcoil 41.

In consideration of the above described points, it is important thatfirst magnetic sheet 44 that is used in non-contact charging module 100has a high level of magnetic permeability and a high saturation magneticflux density so that the L value of charging coil 41 is made as large aspossible. It is sufficient if the magnetic permeability of firstmagnetic sheet 44 is 250 or more and the saturation magnetic fluxdensity thereof is 350 mT or more. In the present embodiment, firstmagnetic sheet 44 is a Mn—Zn ferrite sintered body having a magneticpermeability between 1,500 and 2,500, a saturation magnetic flux densitybetween 400 and 500, and a thickness between approximately 400 µm and700 µm. However, first magnetic sheet 44 may be made of Ni—Zn ferrite,and favorable power transmission can be performed with primary-sidenon-contact charging module 200 as long as the magnetic permeabilitythereof is 250 or more and the saturation magnetic flux density is 350or more.

Charging coil 41 forms an LC resonance circuit through the use of aresonant capacitor. At such time, if the L value of charging coil 41varies significantly between a case where magnet 220 provided inprimary-side non-contact charging module 200 is utilized for alignmentand a case where magnet 220 is not utilized, a resonance frequency withthe resonant capacitor will also vary significantly. Since the resonancefrequency is used for power transmission (charging) between primary-sidenon-contact charging module 200 and non-contact charging module 100, ifthe resonance frequency varies significantly depending on thepresence/absence of magnet 220, it will not be possible to perform powertransmission correctly. However, by adopting the above describedconfiguration, variations in the resonance frequency that are caused bythe presence/absence of magnet 220 are suppressed, and highly efficientpower transmission is performed in all situations.

A further reduction in thickness is enabled by using a Mn—Zn ferritesheet as the ferrite sheet. That is, the frequency of electromagneticinduction is defined by the standard (WPC) as a frequency betweenapproximately 100 kHz and 200 kHz (for example, 120 kHz). A Mn—Znferrite sheet provides a high level of efficiency in this low frequencyband. Note that a Ni—Zn ferrite sheet provides a high level ofefficiency at a high frequency. Accordingly, in the present embodiment,first magnetic sheet 44 that is used for non-contact charging forperforming power transmission at a frequency between approximately 100kHz and 200 kHz is constituted by a Mn—Zn ferrite sheet, and secondmagnetic sheet 45 that is used for NFC communication in whichcommunication is performed at a frequency of approximately 13.56 MHz isconstituted by a Ni—Zn ferrite sheet.

A hole may be formed at the center of center portion 44B of firstmagnetic sheet 44. Note that, the term “hole” may refer to either of athrough-hole and a recessed portion. Although the hole may be larger orsmaller than center portion 44B, it is favorable to form a hole that issmaller than center portion 44B. That is, when charging coil 41 ismounted on the first magnetic sheet, the hole may be larger or smallerthan the hollow portion of charging coil 41. If the hole is smaller thanthe hollow portion of charging coil 41, all of charging coil 41 will bemounted on first magnetic sheet 44.

As described in the foregoing, non-contact charging module is configuredto be adaptable to both a primary-side (charging-side) non-contactcharging module 200 that uses a magnet and primary-side non-contactcharging module 200 that does not use a magnet. Thus, charging can beperformed regardless of the type of primary-side non-contact chargingmodule 200 and convenience is thereby improved. There is a demand tomake the L value of charging coil 41 in a case where magnet 220 isprovided in primary-side non-contact charging module 200 and the L valueof charging coil 41 in a case where magnet 220 is not provided thereinclose to each other, and to also improve both L values. In addition,when magnet 220 is disposed in the vicinity of first magnetic sheet 44,the magnetic permeability of center portion 44B of first magnetic sheet44 that is in the vicinity of magnet 220 decreases. Therefore, adecrease in the magnetic permeability can be suppressed by providing thehole in center portion 44B.

FIG. 7 illustrates a relation between an L value of a charging coil in acase where a magnet is provided in the primary-side non-contact chargingmodule and a case where a magnet is not provided, and the percentage ofhollowing of the center portion. Note that a percentage of hollowing of100% means that the hole in center portion 44B is a through-hole, and apercentage of hollowing of 0% means that a hole is not provided.Further, a percentage of hollowing of 50% means that, for example, ahole (recessed portion) of a depth of 0.3 mm is provided with respect toa magnetic sheet having a thickness of 0.6 mm.

As shown in FIG. 7 , in the case where magnet 220 is not provided inprimary-side non-contact charging module 200, the L value decreases asthe percentage of hollowing increases. At such time, although the Lvalue decreases very little when the percentage of hollowing is from 0%to 75%, the L value decreases significantly when the percentage ofhollowing is between 75% and 100%. In contrast, when magnet 220 isprovided in primary-side non-contact charging module 200, the L valuerises as the percentage of hollowing increases. This is because thecharging coil is less liable to be adversely affected by the magnet. Atsuch time, the L value gradually rises when the percentage of hollowingis between 0% and 75%, and rises significantly when the percentage ofhollowing is between 75% and 100%.

Accordingly, when the percentage of hollowing is between 0% and 75%,while maintaining the L value in a case where magnet 220 is not providedin primary-side non-contact charging module 200, the L value in a casewhere magnet 220 is provided in primary-side non-contact charging module200 can be increased. Further, when the percentage of hollowing isbetween 75% and 100%, the L value in a case where magnet 220 is notprovided in primary-side non-contact charging module 200 and the L valuein a case where magnet 220 is provided in primary-side non-contactcharging module 200 can be brought significantly close to each other.The greatest effect is achieved when the percentage of hollowing isbetween 40 and 60%. Magnet 220 and the first magnetic sheet canadequately attract each other when magnet 220 is provided and the Lvalue of a case where magnet 220 is provided in primary-side non-contactcharging module 200 is increased to 1 µH or more while the L value of acase where no magnet 220 is provided in primary-side non-contactcharging module 200 is maintained.

Regarding Second Magnetic Sheet

Second magnetic sheet 45 illustrated in FIG. 4E is constituted by ametal material such as ferrite, permalloy, sendust or a silicon steelsheet. Ni-based soft magnetic ferrite is preferable as second magneticsheet 45. Second magnetic sheet 45 can be made by molding ferrite fineparticles using a dry pressing method, and sintering the molded ferriteto form a ferrite sintered body having high density. It is preferablethat the density of the soft magnetic ferrite is 3.5 g/cm3 or more.Moreover, it is preferable that the size of the magnetic body made ofthe soft magnetic ferrite is greater than or equal to a crystal grainboundary. Second magnetic sheet 45 is a sheet-like (or a plate-like,film-like, or layer-like) magnetic sheet that is formed to a thicknessbetween approximately 0.07 mm and 0.5 mm. The size of the outer shape ofsecond magnetic sheet 45 is approximately the same as the outer shape ofNFC coil 43. However, it is advantageous to make the outer shape ofsecond magnetic sheet 45 approximately 1 to 3 mm larger than the outershape of NFC coil 43. The thickness of second magnetic sheet 45 is 0.1mm, which is half the thickness or less of first magnetic sheet 44. Themagnetic permeability is at least 100 to 200.

A protective member that is adhered to the upper and lower faces (frontand rear faces) of first magnetic sheet 44 and second magnetic sheet 45may be manufactured by employing at least one means selected from aresin, an ultraviolet curable resin, a visible light-curable resin, athermoplastic resin, a thermosetting resin, a heat-resistant resin,synthetic rubber, a double coated tape, an adhesive layer, and a film,and such means may be selected by considering not only flexibility withrespect to bends and flexures and the like of NFC coil 43, but also heatresistance and moisture resistance and the like. Further, one face, bothfaces, one side-face, both side-faces, or all faces of NFC coil 43 maybe coated with the protective member. In particular, in the presentembodiment, flexibility is provided by previously crushing firstmagnetic sheet 44 and second magnetic sheet 45 into small pieces.Therefore, it is useful to provide a protective sheet so that the largenumber of small pieces that are arranged in a sheet shape do not becomescattered.

Regarding Configuration of Non-Contact Charging Module

FIGS. 8A to 8D illustrate the secondary-side non-contact charging moduleaccording to the present embodiment. FIG. 8A is a top view of thesecondary-side non-contact charging module. FIG. 8B is a bottom view ofthe secondary-side non-contact charging module. FIG. 8C is a sectionalview along a line A-A in FIG. 8A. FIG. 8D is an enlarged sectional viewof an area on the right side of line B—B′ in FIG. 8C.

When the power reception direction of charging coil 41 and thecommunication direction of NFC coil 43 are made the same direction andcharging coil 41 and NFC coil 43 are brought close together, simplydisposing charging coil 41 and NFC coil 43 results in a situation wherethe mutual presence of charging coil 41 and NFC coil 43 reduces thepower transmission efficiency of the counterpart. That is, at a time ofnon-contact charging, there is a possibility that magnetic fluxgenerated by primary-side non-contact charging module 200 will bereceived as transmitted electricity by NFC coil 43, and consequently thepower of the electricity received by charging coil 41 will decrease.Consequently, there is a possibility that the power transmissionefficiency will decrease. Further, as far as NFC coil 43 is concerned,the magnetic flux that primary-side non-contact charging module 200generates is extremely large, and is generated for a long time period.Accordingly, there is a possibility that a current that is too large forNFC coil 43 will arise in NFC coil 43, and there are cases where such acurrent causes adverse effects on NFC coil 43. On the other hand, whenNFC coil 43 communicates, an eddy current is generated in charging coil41 and interferes with the communication of NFC coil 43. That is,because of differences in the size of the power that is transmitted, thediameter of the conducting wire, the number of turns, and the overallsize are larger in charging coil 41 than in NFC coil 43. Consequently,from the viewpoint of NFC coil 43, charging coil 41 is a large metalbody. A magnetic flux that attempts to cancel out a magnetic fluxemitted during communication by NFC coil 43flows through charging coil41, and significantly reduces the communication efficiency of NFC coil43.

Therefore, in the present embodiment, NFC coil 43 is disposed around thecircumference of charging coil 41. Consequently, when performingnon-contact charging, it is difficult for NFC coil 43 to receiveelectricity from magnetic flux that primary-side non-contact chargingmodule 200generates since NFC coil 43 is positioned at a location thatis separated from primary-side non-contact charging module 200, and itis difficult for NFC coil 43 to take power that should be received bycharging coil 41. As a result, a decrease in the power transmissionefficiency can be suppressed. Conversely, in a case where NFC coil 43 isdisposed inside a hollow portion of charging coil 41, since NFC coil 43receives all of the magnetic flux at a time of non-contact charging, NFCcoil 43 takes a lot of power that should be received by charging coil41. Note that, even if charging coil 41 receives magnetic flux duringcommunication by NFC coil 43, the magnetic flux has no influence oncharging coil 41 because the magnetic flux and current are extremelysmall as far as charging coil 41 is concerned. That is, althoughcharging coil 41 generates an eddy current with respect to NFC coil 43,since the eddy current of charging coil 41 does not flow in NFC coil 43to a degree that influences NFC coil 43, NFC coil 43 is placed on theouter side of charging coil 41 and the opening area is made large tothereby improve the communication efficiency of NFC coil 43.

Further, when NFC coil 43 communicates, since charging coil 41 isdisposed on the inner side thereof, the region of charging coil 41 thatis adjacent to NFC coil 43 is small relative to the size of NFC coil 43.As a result, it is difficult for an eddy current to arise in chargingcoil 41. Conversely, if charging coil 41 is disposed on the outer side,charging coil 41 will be larger than the small NFC coil 43, and as aresult the region of charging coil 41 that is adjacent to NFC coil 43will be relatively larger. Therefore, an eddy current that arises incharging coil 41 will be extremely large as far as NFC coil 43 isconcerned, and the communication of NFC coil 43 will be significantlyinterfered with. Note that, even if an eddy current arises in NFC coil43 during non-contact charging, the eddy current will be small as far ascharging coil 41 is concerned and will therefore not affect chargingcoil 41.

First magnetic sheet 44 has a frequency characteristic that can improvepower transmission of electromagnetic induction between approximately100 and 200 kHz that performs non-contact charging. However, when thereis a peak at approximately 100 to 200 kHz, communication of NFC coil 43can also be improved at the 13.56 MHz band at which NFC communication isperformed. On the other hand, second magnetic sheet 45 has a frequencycharacteristic that can improve communication of electromagneticinduction at a frequency of approximately 13.56 MHz at which NFC coil 43performs communication. However, when there is a peak at approximately13.56 MHz, there is almost no influence on the efficiency of non-contactcharging in a band of approximately 100 to 200 kHz at which non-contactcharging is performed.

With respect to NFC coil 43 and charging coil 41, by disposing chargingcoil 41 at a hollow position (a hollow portion and a lower part of thehollow portion) of NFC coil 43, first magnetic sheet 44 can be utilizedto improve the communication of NFC coil 43. That is, while achieving areduction in size by modularization of first magnetic sheet 44, secondmagnetic sheet 45, charging coil 41, and NFC coil 43, first magneticsheet 44 can also be utilized for a different purpose (improving theefficiency of NFC coil 43) than the original purpose thereof (improvingthe efficiency of charging coil 41), and thus first magnetic sheet 44can be efficiently utilized.

As a result, an induction voltage when a magnetic flux was received fromthe same NFC reader/writer changed as described below. For example,whereas the induction voltage was 1,573 mV in a case where NFC coil 43was placed on a magnetic sheet having a through-hole in a regioncorresponding to a hollow portion of NFC coil 43, the induction voltagewas 1,712 mV in the case of non-contact charging module 100 illustratedin FIG. 7A. The reason for this was that first magnetic sheet 44improved the communication efficiency of NFC coil 43.

Furthermore, as shown in FIG. 8A, distance d1 between corner portions441 a to 441 d at the four corners of the substantially square NFC coil43 and corner portions 431 a to 431 d at the four corners of thesubstantially square charging coil 41 is wider than distance d2 betweenother portions (between the respective sides). That is, althoughdistance d2 between a side portion of NFC coil 43 and a side portion ofcharging coil 41 that are adjacent is narrow, distance d1 between cornerportions 441 a to 441 d and corner portions 431 a to 431 d is large. Thereason is that, in comparison to corner portions 441 a to 441 d of NFCcoil 43, corner portions 431 a to 431 d of charging coil 41 curvegradually (have a large R) and thereby shift inward.

Further, in the case of charging coil 41 and NFC coil 43 that have asubstantially rectangular shape, magnetic flux concentrates at cornerportions 431 a to 431 d and corner portions 441 a to 441 d thereof.Therefore, if distance d1 between corner portions 431 a to 431 d andcorner portions 441 a to 441 d is large, it is possible to suppress theoccurrence of a situation in which the respective magnetic fluxes aretaken by the other coil. That is, by causing the outermost edges ofcorner portions 431 a to 431 d of charging coil 41 to curve moregradually (by setting R to a large value) than the innermost edges ofcorner portions 441 a to 441 d of NFC coil 43, distance d1 betweencorner portions 441 a to 441 d and corner portions 431 a to 431 d thatare facing can be made larger than distance d2 between side portionsthat are facing. Consequently, non-contact charging module 100 can bereduced in size by bringing the side portions at which the magnetic fluxdoes not concentrate close to each other, and the respectivecommunication (power transmission) efficiencies of the charging coil 41and NFC coil 43 can be improved by separating the respective cornerportions thereof. Note that, R of corner portions 431 a to 431 d ofcharging coil 41 is approximately 2 mm with respect to the innermostedge (hollow portion) and is approximately 5 mm to 15 mm with respect tothe outermost edge, and R of corner portions 441 a to 441 d of NFC coil43 is approximately 0.1 mm with respect to the innermost edge (hollowportion) and is approximately 0.2 mm with respect to the outermost edge.Further, in the present embodiment, distance d1 between corner portions431 a to 431 d and corner portions 441 a to 441 d is 2 mm, and may beapproximately 1.5 mm to 10 mm, and distance d2 between facing sideportion is 1 mm, and may be approximately 0.5 mm to 3 mm. Further,preferably, by making d1 a distance that is between three and seventimes greater than d2, a favorable balance can be achieved between areduction in size, improvement of power transmission efficiency, andimprovement of communication efficiency.

By forming charging coil 41 as a rectangle, although charging coil 41comes close to NFC coil 43 at the side portions of the rectangularportion, a wide opening area can be secured. In contrast, if chargingcoil 41 is wound in a circular shape, the portions that come close to(portions closest to) NFC coil 43 are points, and not sides, and hencemutual interference therebetween can be mitigated. That is, a distancebetween the four corners of NFC coil 43 and the four corners of chargingcoil 41 increases. As a result, the distance between charging coil 41and the four corners at which the magnetic flux concentrates most in NFCcoil 43 increases, and thus the communication efficiency of NFC coil 43can be improved. In addition, by forming charging coil 41 in a circularshape, regardless of what direction charging coil 41 and primary-sidecoil 210 of primary-side non-contact charging module 200 face eachother, charging can be performed without being influenced by thedirection.

Further, since charging coil 41 is disposed in a hollow portion of NFCcoil 43, leg portions 432 a and 432 b and NFC coil 43 are stacked, sothat the thickness of secondary-side non-contact charging module 20increases. In particular, since charging coil 41 is considerably thickin the thickness direction compared NFC coil 43, the thickness ofsecondary-side non-contact charging module 20 will become extremelythick if leg portion 432 a and leg portion 432 b of charging coil 41 arestacked on another portion of secondary-side non-contact charging module20. Therefore, both of leg portions 32 a and 32 b are housed in slit 48of first magnetic sheet 44. At least a part of leg portion 432 a thatconnects to winding start (inner side) point 432 aa of the windingportion (planar coil portion) of charging coil 41 is stacked with boththe winding portion (planar coil portion) of charging coil 41 and NFCcoil 43. Further, at least a part of leg portion 432 b that connects towinding end (outer side) point 432 bb of the winding portion (planarcoil portion) of charging coil 41 is stacked with NFC coil 43.Therefore, slit 48 is extended from lower edge 414 shown in FIG. 8B toat least winding start (inner side) point 432 bb of the winding portion(planar coil portion) of charging coil 41. A portion of leg portion 432a that is stacked with the winding portion (planar coil portion) ofcharging coil 41 and the NFC coil 43 is housed in slit 48. Further, aportion of leg portion 432 b that is stacked with the NFC 43 coil ishoused in slit 48. It is thereby possible to prevent a situation wherethe thickness increases at a portion at which conducting wires arestacked together by storing both of leg portions 432 a and 432 b in slit48. Also, because NFC coil 43 and charging coil 31 are in rectangularshape, slit 48 is perpendicular to straight portions of NFC coil 43 andcharging coil 41. Thus, slit 48 can be formed shortly, and the powertransmission efficiency of charging coil 41 and the communicationefficiency of NFC coil 43 are improved.

As described above, slit 48 may be a penetrating slit or may be a slitformed as a recessed portion having a bottom. It is sufficient to atleast form slit 48 to be deeper than the diameter of the conducting wireof charging coil 41. The lateral width (width in the short-sidedirection) of slit 48 is 5 mm, and a preferable lateral width is between2 mm and 10 mm. In the present embodiment, a minimum necessary width forhousing both of leg portions 32 a and 32 b is 2 mm. The lateral width ofslit 48 is preferably an amount that is from two to five times greaterthan the amount of a diameter that corresponds to twice the diameter ofthe conducting wire of charging coil 41. That is, it is preferable that,even if the conducting wire is formed of a plurality of wires such as inthe case of a litz wire, slit 48 has a width such that around fourterminals of charging coil 41 can be housed therein. If the width ofslit 48 is made larger than that, the power transmission efficiency ofcharging coil 41 will decrease. The reason the width is set to twice ormore the minimum required width is to provide a gap between leg portions432 a and 432 b. It is thereby possible to reduce stray capacitancebetween leg portion 432 a and leg portion 432 b. As a result, theefficiency of charging coil 41 can be improved. Further, it is easy tohouse leg portions 432 a and 432 b inside slit 48, and the strength ofleg portions 32 a and 32 b can be improved.

By housing both of leg portions 32 a and 32 b inside a single slit 48,it is possible to suppress to the minimum the area removed from firstmagnetic sheet 44 to form a slit. However, a plurality of slits 11 mayalso be provided depending on the direction in which leg portions 432 aand 432 b extend. That is, slit 48 that houses leg portion 432 a thatconnects with winding start (inner side) point 432 aa of the windingportion (planar coil portion) of charging coil 41 is extended from loweredge 414 to at least winding start (inner side) point 432 aa of thewinding portion (planar coil portion) of charging coil 41. The portionof leg portion 432 a that is stacked with the winding portion (planarcoil portion) of charging coil 41 and NFC coil 43 is housed in slit 48.On the other hand, a slit that houses leg portion 432 b that connectswith winding end (outer side) point 432 bb of the winding portion(planar coil portion) of charging coil 41 is extended from lower edge414 to at least winding end (outer side) point 432 bb of the windingportion (planar coil portion) of charging coil 41. The portion of legportion 432 b that is stacked with NFC coil 43 is housed in slit 48. Byproviding two slits and housing leg portion 432 a and leg portion 432 bin one slit each in this manner, the generation of stray capacitancebetween leg portions 432 a and 432 b can be avoided. The direction inwhich to draw out leg portion 432 a and leg portion 432 b can be freelyset. In the case of forming two slits that house only one conductingwire each, each slit is approximately 0.5 mm.

A configuration may be adopted in which a first slit is formed at only aportion at which leg portion 432 a is stacked with the winding portion(planar coil portion) of charging coil 41, and a second slit that housesleg portion 432 a and leg portion 432 b is formed at a portion at whichleg portion 432 a and leg portion 432 b are stacked with NFC coil 43.That is, slit 48 may be formed in any shape, and the important point isthat both of leg portion 432 a and leg portion 432 b are housed in slit48.

Slit 48 may also be formed in an L shape as shown in FIG. 9 . FIG. 9 isa schematic diagram illustrating a first magnetic sheet having anL-shaped slit according to the present embodiment. In the L-shaped slit(hereunder, referred to as “slit 48a”) shown in FIG. 9 , region xcorresponds to slit 48 shown in FIG. 4D and houses leg portions 432 aand 432 b. The reason that slit 48 a is enlarged as far as region y andregion z is that, as described in the foregoing, the conducting wireshown in FIG. 4B is formed to curve more gradually and to a greaterdegree at winding end point 431 bb than at winding start point 431 aa.Because the conducting wire curves gradually at winding end point 432bb, slit 48 a is enlarged as far as region y to house the curvedportion. It is not necessary to enlarge slit 48 a as far as region z.However, in the present embodiment, because first magnetic sheet 44 isconstituted by a ferrite sheet (sintered body), if region z is left as apart of first magnetic sheet 44 and is not made a part of slit 48 a, theportion of the sheet at region z will be damaged. Therefore, slit 48 ais formed as far as region z to prevent damaging of first magnetic sheet44 and stabilize the characteristics of first magnetic sheet 44. Notethat, if first magnetic sheet 44 is damaged, the characteristics offirst magnetic sheet 44 will change significantly, and thecharacteristics of charging coil 41 will also change significantly. Forexample, the L value will decrease and the power transmission efficiencyof non-contact charging will decrease. FIG. 9 illustrates that the firstmagnetic sheet 44 has four edges 44 a-44 d that collectively define arectangular profile of the magnetic sheet 44, wherein at most threepairs of adjacent edges respectively meet to form at most three corners46 a-46 c. As illustrated, adjacent edges 44 a and 44 b meet to form acorner 46 a, adjacent edges 44 b and 44 c meet to form a corner 46 b,and adjacent edges 44 c and 44 d meet to form a corner 46 c, whileadjacent edges 44 a and 44 d do not meet each other and do not form acorner. Still referring to FIG. 9 , the magnetic sheet 44 has arectangular shape including four edges 44 a-44 d and four cornerportions 46 a-46 d. Each pair of adjacent edges forms a virtual corner46 a′-46 d′, and each corner portion (46a-46d) is receded inwardly fromits corresponding virtual corner (46 a′-46 d′) by a receding distance.At least one of four receding distances (e.g., distance 46 d′-46 d) isgreater than another one of the four receding distances (e.g., distance46 a′-46 a). Still referring to FIG. 9 , the magnetic sheet 44 includesfour sides 44 a-44 d that collectively define a rectangular profile ofthe magnetic sheet 44. The four sides 44 a-44 d consist of a first side44 b and a second side 44 d in parallel to each other, and a third side44 c and a fourth side 44 a in parallel to each other. The third side 44c is interposed between the first side 44 b and the second side 44 d.The first side 44 b is longer than the second side 44 d, and the thirdside 44 c is longer than the fourth side 44 a.

Next, the frequency characteristics of the first magnetic sheet and thesecond magnetic sheet will be described. The term “frequency” refers tothe frequency of an antenna (for example, charging coil 41 or NFC coil43) that includes the magnetic sheet. FIGS. 10A to 10C illustratefrequency characteristics of the first magnetic sheet and the secondmagnetic sheet according to the present embodiment. FIG. 10A illustratesa frequency characteristic of the magnetic permeability of firstmagnetic sheet 44 (Mn—Zn ferrite sintered body). FIG. 10B illustrates afrequency characteristic of the magnetic permeability of second magneticsheet 45 (Ni—Zn ferrite sintered body). FIG. 10C illustrates a frequencycharacteristic of a Q value of second magnetic sheet 45.

In the present embodiment, as shown in FIG. 8C, second magnetic sheet 45is stacked on the upper face of first magnetic sheet 44. As shown inFIGS. 10A to 10C, second magnetic sheet 45 has favorable characteristics(a high Q value and a magnetic permeability of around 125) at a highfrequency (13.56 MHz) that is used for communication by NFC coil 43,whereas first magnetic sheet 44 has a favorable characteristic (magneticpermeability of around 1,700) at a low frequency (100 to 200 kHz) thatis used for power transmission by charging coil 41. Therefore, normally,the communication efficiency of NFC coil 43 will be improved by formingonly second magnetic sheet 45 in a thick manner directly below NFC coil43. However, in the present embodiment, first magnetic sheet 44 isextended as far as the area directly below NFC coil 43 to improve thepower transmission efficiency of charging coil 41. This is because ofthe frequency characteristics of the respective ferrite sheets. First,first magnetic sheet 44 that is used for non-contact charging of a largeamount of transmitted power is generally a high-magnetic permeabilitymaterial for ensuring sufficient power transmission efficiency. On theother hand, magnetic permeability of the level required for firstmagnetic sheet 44 is not necessary with respect to second magnetic sheet45 for NFC communication that transmits a small amount of power.Therefore, first magnetic sheet 44 also has the magnetic permeabilityrequired for NFC communication in a communication frequency band for NFCcommunication. That is, the overall magnetic permeability of firstmagnetic sheet 44 that supports non-contact charging is highirrespective of the frequency in comparison to second magnetic sheet 45that supports NFC communication. As shown in FIG. 10A, even when thefrequency is around 13.56 MHz, magnetic permeability µ of first magneticsheet 44 is about 500, and first magnetic sheet 44 can adequatelyfunction as a magnetic sheet. In particular, first magnetic sheet 44 inthe present embodiment that is described above can adequately fulfill arole as a magnetic sheet. In contrast, as shown in FIG. 10B, when thefrequency is between 100 kHz to 200 kHz, second magnetic sheet 45 doesnot have sufficient magnetic permeability for non-contact charging(magnetic permeability of around 125).

Therefore, in order to improve and maintain the communication efficiencyof both charging coil 41 and NFC coil 43, it is favorable to adopt aconfiguration in which the region directly below NFC coil 43 is astacked structure that includes first magnetic sheet 44 and secondmagnetic sheet 45. It is thereby possible to improve the communicationefficiency of both coils. That is, by making first magnetic sheet alarge size, the power transmission efficiency of non-contact charging isimproved and NFC communication is also adequately supported. The reasonthat second magnetic sheet for NFC communication is also provided, andnot just first magnetic sheet 44, is to improve the Q value of NFCcommunication by NFC coil 43. As shown in FIG. 10C, because secondmagnetic sheet 45 has a favorable Q value, the communication distance ofthe NFC communication can be increased.

Also, as shown in FIGS. 8A to 8D, NFC coil 43 and the whole area ofsecond magnetic sheet 45 are placed on first magnetic sheet 44. Thus,there is first magnetic sheet 44 is under the whole area of secondmagnetic sheet 45 and the communication efficiency of NEC coil 43 isimproved. In this case, the outer shape of second magnetic sheet 45 issame size as or smaller size than first magnetic sheet 44.

Further, parts of NFC coil 43 and second magnetic sheet 45 are placed onfirst magnetic sheet 44, and the rest of NFC coil 43 and second magneticsheet 45 may protrude outside the first magnetic sheet 44. The outershape of second magnetic sheet 45 is larger than first magnetic sheet44, or the center of the first magnetic sheet 44 and the center of thesecond magnetic sheet 45 may be misaligned. However, larger area of NFCcoil 43 and second magnetic sheet 45 are preferable to be stacked onfirst magnetic sheet 44. Also, the center of the first magnetic sheet 44and the center of the second magnetic sheet 45 are preferable to bealigned. However, when NFC coil 43 and second magnetic sheet 45 are toolarge to be placed on first magnetic sheet 44, a part of NFC coil 43 andsecond magnetic sheet 45 may protrude outside first magnetic sheet 44.Thus, the opening area of NFC coil 43 does not depend on the area offirst magnetic sheet 44 and is large. As a result, the communicationefficiency of NFC coil 43 is improved, and secondary-side non-contactcharging module 20 may be downsized despite of the size of NFC coil43because first magnetic sheet does not need to be formed largely.

In addition, while the thickness of first magnetic sheet 44 is 0.43 mm,second magnetic sheet 45 is a relatively thin 0.1 mm, which is less thanhalf the thickness of first magnetic sheet 44. The diameter of theconducting wire of second magnetic sheet 45 is thinner than that ofcharging coil 41 (about 0.2 mm to 1.0 mm).

Furthermore, it is sufficient that at least a part of second magneticsheet 45 and NFC coil 43 are mounted on first magnetic sheet 44, and itis not necessary to mount all of second magnetic sheet 45 and NFC coil43 thereon. On the other hand, it is better for all of NFC coil 43 to bemounted on second magnetic sheet 45. It is thereby possible to improvethe communication efficiency of NFC coil 43. However, it is favorable tomake the opening area of NFC coil 43 large to improve the communicationefficiency of NFC coil 43, and in such case an effect can be obtained byenlarging only second magnetic sheet 45 and NFC coil 43.

Next, design of the inside of secondary-side non-contact charging module20 is described.

As described in FIGS. 2A and 2B, secondary-side non-contact chargingmodule 20 is arranged at position 11B in housing 11 and does not overlapwith camera unit 16 in a plane normal to the thickness direction ofhousing 11 (the direction of arrow A).

Further, secondary-side non-contact charging module 20 is arrangedwithin a dimension L1 of the camera unit 16 along the thicknessdirection of the housing 11.

Furthermore, secondary-side non-contact charging module 20 is arrangedat position 11B in housing 11 and does not overlap with battery pack 18in a plane normal to the thickness direction of housing 11 (thedirection of arrow A). And, secondary-side non-contact charging module20 is arranged within a dimension L2 of the battery pack 18 in a planenormal to the thickness direction of housing 11 (the direction of arrowA).

Thus, secondary-side non-contact charging module 20 is arranged atposition 11B in housing 11 and does not overlap with camera unit 16 andbattery pack 18. Also, secondary-side non-contact charging module 20 isarranged within the dimension L1 of the camera unit 16 and the dimensionL2 of the battery pack 18 in a plane normal to the thickness directionof housing 11 (the direction of arrow A). Thus, the mobile terminal 10may be downsized.

Further, secondary-side non-contact charging module 20 may be arrangedcloser to housing 11 because secondary-side non-contact charging module20 is arranged at position 11B where secondary-side non-contact chargingmodule 20 does not overlap with camera unit 16 and battery pack 18.

FIG. 3 describes a relation of mobile terminal 10 and charger 50 whenmobile terminal 10 is brought close to charger 50 which includesprimary-side non-contact charging module for power transmission.Secondary-side non-contact charging module 20 is arranged so that atleast a part of secondary-side non-contact charging module 20 is within2.5 mm from an outer wall surface adjacent to charger 50 of housing 11.

Accordingly, as described in FIG. 12 , primary-side non-contact chargingmodule 52 of charger 50 and secondary-side non-contact charging module20 of mobile terminal 10 may be arranged close to each other duringpower transmission. Thus, the power transmission efficiency betweenmobile terminal 10 and charger 50 may be improved. Further, thecommunication efficiency between mobile terminal 10 and charger 50 maybe also improved.

Furthermore, as described in FIG. 2 , secondary-side non-contactcharging module 20 is arranged to overlap with a cross point 58 betweena center line 55 extending in parallel to an interface between the firstarea 31 and the second area 32 and a center line 56, which extendsorthogonal to the interface of the second area 32 and extends in a widthdirection of the housing 11.

The direction of the interface between the first area 31 and the secondarea 32 is same as a direction of an arrow C. Also, the width direction,which is orthogonal to the direction of the interface of the second area32, of housing is same as a direction of an arrow B.

Battery pack 18 and secondary-side non-contact charging module 20 arearranged adjacent to each other by arranging battery pack 18 in thefirst area 31 of housing 11 and arranging secondary-side non-contactcharging module 20 in the second area 32. Thus, connecting battery pack18 to secondary-side non-contact charging module 20 may be easy.

Furthermore, secondary-side non-contact charging module 20 is arrangedto overlap with the cross point 58 of a center line 55 extending inparallel to the interface between the first area 31 and the second area32 (the direction of arrow C) and a center line 56 of the widthdirection (the direction of arrow B) of housing 11.

This may avoid weight imbalance of secondary-side non-contact chargingmodule 20 in housing 11 and avoid causing discomfort to a user. Also,the user may charge the mobile terminal by placing the side of thehousing of the mobile terminal on the charger.

As described in FIG. 3 , heat dissipating sheet 22 is provided on firstmagnetic sheet 33 arranged on a side the secondary-side non-contactcharging module 20 facing the circuit board 14.

The heat dissipating sheet 22 is provided on first magnetic sheet 33(i.e. secondary-side non-contact charging module 20) and is in contactwith the shield case 36. Thus, the heat of secondary-side non-contactcharging and base substrate 34 (circuit board 14) module 20 may bedissipated easily.

Next explanation is about the second embodiment and the third embodimentaccording to FIGS. 13 and 14 .

In the second embodiment and the third embodiment, same parts as mobileterminal of the first embodiment are assigned same number as the firstembodiment and not explained.

The Second Embodiment

As shown in FIG. 13 , secondary-side non-contact charging module 20 isarranged to overlap with a cross point 63 between the center line 55 ofthe second area 32 and a center line 62 (the direction of arrow B) whichextends orthogonal to the interface and extends in a width direction ofthe battery pack 18.

Other constitution of mobile terminal 60 is same as mobile terminal 10of the first embodiment.

Arranging secondary-side non-contact charging module 20 to overlap withthe cross point 63 between the center line 55 of the second area 32 andthe center line 62 which extends in the width direction of the batterypack 18 may avoid weight imbalance caused by secondary-side non-contactcharging module 20 in housing 11.

In particular, weight imbalance caused by secondary-side non-contactcharging module 20 in the interface direction of battery pack 18 andcausing discomfort to a user may be avoided. Also, the user may chargethe mobile terminal by placing the side of the housing of the mobileterminal on the charger.

The Third Embodiment

As shown in FIG. 14 , regarding mobile terminal 70 of the thirdembodiment, secondary-side non-contact charging module 72 is arranged ona side closer to the first area 31 relative to the center line 55 of thesecond area 32. Other constitution of mobile terminal 60 is same asmobile terminal 10 of the first embodiment.

Arranging secondary-side non-contact charging module 20 on a side closerto the first area 31 relative to the center line 55 of the second area32 may avoid weight imbalance of secondary-side non-contact chargingmodule 20.

In particular, weight of secondary-side non-contact charging module 20is not biased to an opposite side of the first area 31 relative to thecenter line of the second area 32. Thus, causing discomfort to a usermay be avoided. Also, the user may charge the mobile terminal by placingthe side of the housing of the mobile terminal on the charger.

The Fourth Embodiment

In FIGS. 2A and 2B, secondary-side non-contact charging module 20 isarranged adjacent to camera unit 16. However, camera unit 16 may bearranged in a through hole which is formed in secondary-side non-contactcharging module 20. Also, a part of NFC coil 43 may surround the thoughhole when the though hole is formed in secondary-side non-contactcharging module 20.

In the above structure, NFC coil 43 has the wound wire which is large inlength by use of a space around camera unit 16 and an antennacharacteristic may be improved.

The mobile terminal of the present invention is not limited to the aboveembodiment and may be changed or improved appropriately.

For example, shapes and structures of the mobile terminal, the housing,the communicating hole, the circuit board, the camera unit, theprimary-side non-contact charging module, the secondary-side non-contactcharging module, the charging coil, the NFC coil, the first magneticsheet, the second magnetic sheet, and the like are not limited to whatis described and may be changed.

INDUSTRIAL APPLICABILITY

The present invention is useful for various kinds of electronic devicessuch as a mobile terminal, in particular, portable devices such as amobile phone, a portable audio device, a personal computer, a digitalcamera, and a video camera which include the non-contact charging modulethat includes a non-contact charging module and an NFC antenna.

REFERENCE SIGNS LIST 10, 60, 70 mobile terminal 11 housing 12communicating hole 14 circuit board 16 camera unit 20, 72 secondary-sidenon-contact charging module (non-contact charging module) 22 heatdissipating sheet 41 charging coil 42 wire 43 NFC coil 44 first magneticsheet 45 second magnetic sheet

What is claimed is:
 1. 1. A mobile terminal, comprising: a housinghaving a circuit board, a battery, a charging coil and a sheet includedtherein, the charging coil including a winding portion and two legportions, and the sheet including four edges and four corner portions;wherein a first one of said corner portions has a corresponding firstvirtual comer; wherein said first virtual corner is formed by a pair ofadjacent edges of the sheet that do not meet each other and do not forma corner; and wherein the first one of said corner portions is recededinwardly from said first virtual corner by a first receding distance. 2.The mobile terminal of claim 1, wherein one or more of the cornerportions of the sheet other than the first one of said corner portionseach has a corresponding respective virtual corner.
 3. The mobileterminal of claim 2, wherein said one or more of the corner portions ofthe sheet other than the first one of said corner portions are eachreceded inwardly from their corresponding respective virtual corner by arespective receding distance.
 4. The mobile terminal of claim 3, whereinthe first receding distance is greater than the respective recedingdistances of said one or more of the corner portions of the sheet otherthan the first one of said corner portions.
 5. The mobile terminal ofclaim 3, wherein the first receding distance is different than therespective receding distances of said one or more of the corner portionsof the sheet other than the first one of said corner portions.
 6. Themobile terminal of claim 1, wherein the sheet is a magnetic sheet. 7.The mobile terminal of claim 6, wherein one or more of the cornerportions of the sheet other than the first one of said corner portionseach has a corresponding respective virtual corner.
 8. The mobileterminal of claim 7, wherein said one or more of the corner portions ofthe sheet other than the first one of said corner portions are eachreceded inwardly from their corresponding respective virtual corner by arespective receding distance.
 9. The mobile terminal of claim 8, whereinthe first receding distance is greater than the respective recedingdistances of said one or more of the corner portions of the sheet otherthan the first one of said corner portions.
 10. The mobile terminal ofclaim 8, wherein the first receding distance is different than therespective receding distances of said one or more of the corner portionsof the sheet other than the first one of said corner portions.
 11. Themobile terminal of claim 1, wherein the charging coil is formed in oneof: a circular chape, an oval shape, and a rectangular shape.
 12. Themobile terminal of claim 11, wherein the housing has a substantiallyrectangular shape in a plan view of the housing.
 13. The mobile terminalof claim 1, wherein the housing further includes a near fieldcommunication (NFC) coil arranged adjacent to the charging coil on thesheet.
 14. The mobile terminal of claim 1, wherein the housing furtherincludes a communication coil having a conducting wire pattern-printedon a substrate.
 15. The mobile terminal of claim 1, wherein the circuitboard has a thickness direction orthogonal to a plane of the circuitboard, and the charging coil is included in a charging module thatoverlaps with the circuit board as viewed in the thickness direction ofthe circuit board.
 16. The mobile terminal of claim 15, wherein thehousing further includes a communication coil.
 17. The mobile terminalof claim 16, wherein one or more of the corner portions of the sheetother than the first one of said corner portions each has acorresponding respective virtual corner.
 18. The mobile terminal ofclaim 17, wherein said one or more of the corner portions of the sheetother than the first one of said corner portions are each recededinwardly from their corresponding respective virtual corner by arespective receding distance.
 19. The mobile terminal of claim 18,wherein the first receding distance is greater than the respectivereceding distances of said one or more of the corner portions of thesheet other than the first one of said corner portions.
 20. The mobileterminal of claim 18, wherein the first receding distance is differentthan the respective receding distances of said one or more of the cornerportions of the sheet other than the first one of said corner portions.21. A mobile terminal, comprising a housing having a circuit board, abattery, a charging coil and a sheet included therein, the charging coilincluding a winding portion and two leg portions and the sheet includinga number of corner portions corresponding to respective virtual corners,said corner portions including a first corner portion having acorresponding first virtual corner formed by a pair of adjacent edges ofthe sheet that do not form a corner, wherein said first corner portionof the sheet is receded inwardly from said first virtual corner by afirst receding distance.
 22. The mobile terminal of claim 21, whereinone or more of the corner portions of the sheet other than said firstcorner portion are each receded inwardly from their correspondingrespective virtual corner by a respective receding distance.
 23. Themobile terminal of claim 21, wherein the first receding distance isgreater than the respective receding distances of said one or more ofthe corner portions of the sheet other than the first one of said cornerportions.
 24. The mobile terminal of claim 21, wherein the firstreceding distance is different than the respective receding distances ofsaid one or more of the corner portions of the sheet other than thefirst one of said corner portions.
 25. The mobile terminal of claim 21,wherein the sheet is a magnetic sheet.
 26. The mobile terminal of claim25, wherein one or more of the corner portions of the sheet other thansaid first corner portion are each receded inwardly from theircorresponding respective virtual corner by a respective recedingdistance.
 27. The mobile terminal of claim 26, wherein the firstreceding distance is greater than the respective receding distances ofsaid one or more of the corner portions of the sheet other than thefirst one of said corner portions.
 28. The mobile terminal of claim 26,wherein the first receding distance is different than the respectivereceding distances of said one or more of the corner portions of thesheet other than the first one of said corner portions.